This invention relates to a throttle assembly for controlling the supply of air to an engine and for providing idle air control during periods when the engine is idling.
In order to ensure proper control of vehicle engine emissions, and maximize fuel economy, modern automotive vehicles idle at relatively low engine speeds. However, when vehicle assessories are switched on, a slowly idling engine may stall. Accordingly, it is necessary to provide a device which permits engine idle speed to vary as a function of the load on the engine. Characteristic of these prior devices are idle bypass valves. These devices open and close a passage, formed in a throttle body, extending around the throttle plate to "bypass" air about the throttle plate during instances when the throttle plate is substantially closed. Illustrative of one of these prior devices is the commonly assigned U.S. Pat. No. 4,388,856. Another prior device is the vacuum actuator disclosed in U.S. Pat. No. 4,448,659.
Accordingly, the present invention comprises: a throttle assembly comprising: means for establishing an air intake passage; means for controlling the flow of air to an engine. Such air flow control means including primary means, rotatably mounted in the passage means, and rotatable from a substantially closed position at engine idle speed conditions, to a substantially open position at wide open throttle conditions, for varying the flow area of the passage means and secondary means, rotatably mounted relative to the primary means, for varying the flow area of a secondary air flow passage to permit air to flow directly across and through such primary means. More specifically the invention comprises: a throttle assembly for an engine including:
a primary throttle plate rotatably mounted on a first shaft; means for rotating the first shaft in response to operator demand; a second throttle plate received within a cut-out formed in the first throttle plate and rotatably mounted relative to the first shaft; and means for rotating the second throttle plate relative to the first throttle plate.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.